ISO 17776 MAH Bow-Tie and EI AVIFF Flow-Induced Vibration Screening

Class Purpose Standard
MahCatalogue Pre-defined threats, consequences and barriers per MAH type ISO 17776
MahBowTieBuilder Assemble a BowTieModel for a major-accident hazard ISO 17776
PipingFivScreening Likelihood-of-failure screening for flow-induced vibration Energy Institute AVIFF
FivLikelihoodResult LOF score and likelihood band for one circuit Energy Institute AVIFF

Classes live under neqsim.process.safety.hazid and neqsim.process.safety.vibration.

MAH bow-tie from the ISO 17776 catalogue

MahBowTieBuilder.build(MahType) returns a fully populated BowTieModel (threats on the left, consequences on the right, barriers in the middle) for a standard major-accident-hazard type:

import neqsim.process.safety.hazid.MahType;
import neqsim.process.safety.hazid.MahBowTieBuilder;
import neqsim.process.safety.hazid.MahCatalogue;
import neqsim.process.safety.risk.bowtie.BowTieModel;

BowTieModel bowtie = MahBowTieBuilder.build(MahType.TOPSIDE_HYDROCARBON_RELEASE);

String hazard = bowtie.getHazardId();
bowtie.getThreats();        // ≥ 4 threats, each with getFrequency()
bowtie.getConsequences();   // ≥ 3 consequences
bowtie.getBarriers();       // ≥ 5 barriers, each with getPfd()

// Inspect the raw catalogue entries directly
MahCatalogue.threatsFor(MahType.TOPSIDE_HYDROCARBON_RELEASE);
MahCatalogue.consequencesFor(MahType.TOPSIDE_HYDROCARBON_RELEASE);
MahCatalogue.barriersFor(MahType.TOPSIDE_HYDROCARBON_RELEASE);

Default threat frequency and barrier PFD are exposed as MahBowTieBuilder.DEFAULT_THREAT_FREQUENCY and MahBowTieBuilder.DEFAULT_BARRIER_PFD. MahType covers TOPSIDE_HYDROCARBON_RELEASE, RISER_LEAK, WELL_BLOWOUT, STRUCTURAL_COLLAPSE, DROPPED_OBJECT, HELICOPTER_LOSS, SHIP_COLLISION, FIRE_EXPLOSION, TOXIC_RELEASE, LOSS_OF_BUOYANCY, and EXTREME_WEATHER, each carrying a human-readable description.

EI AVIFF flow-induced-vibration screening

PipingFivScreening computes an Energy Institute AVIFF likelihood-of-failure (LOF) score for a piping circuit and maps it to a likelihood band. Use screenGas or screenLiquid depending on the fluid:

import neqsim.process.safety.vibration.PipingFivScreening;
import neqsim.process.safety.vibration.PipingFivLikelihood;
import neqsim.process.safety.vibration.FivLikelihoodResult;

// Gas circuit: tag, rho[kg/m3], v[m/s], D[m], wall t[m], nBranches, pulsation, support
FivLikelihoodResult gas = PipingFivScreening.screenGas(
    "Compressor discharge", 80.0, 30.0, 0.3, 0.006, 2, 4.0, 2.0);

double lof = gas.getLofScore();
PipingFivLikelihood band = gas.getLikelihood();   // LOW / MEDIUM / HIGH / VERY_HIGH
String json = gas.toJson();                        // contains "lofScore", "likelihood"

// Liquid circuit: tag, v[m/s], D[m], wall t[m], nBranches, support
FivLikelihoodResult liquid = PipingFivScreening.screenLiquid(
    "Pump discharge", 3.5, 0.15, 0.005, 1, 1.5);

// Map an arbitrary LOF score to a band
PipingFivLikelihood b = PipingFivScreening.bandFor(0.7);   // HIGH

The likelihood bands are LOW (< 0.3), MEDIUM (0.3–0.5), HIGH (0.5–1.0), and VERY_HIGH (≥ 1.0). Invalid geometry (zero diameter, negative velocity) throws IllegalArgumentException.

Verification

./mvnw test -Dtest=MahBowTieBuilderTest,PipingFivScreeningTest